commit ae5defc04e383b92b7828833783b36d1d49c188c
Author: Torvald Riegel <triegel@redhat.com>
Date: Wed Oct 29 10:34:36 2014 +0100
Fix atomic_full_barrier on x86 and x86_64.
This fixes BZ #17403 by defining atomic_full_barrier,
atomic_read_barrier, and atomic_write_barrier on x86 and x86_64. A full
barrier is implemented through an atomic idempotent modification to the
stack and not through using mfence because the latter can supposedly be
somewhat slower due to having to provide stronger guarantees wrt.
self-modifying code, for example.
@@ -12,18 +12,18 @@ Version 2.22
438, 4719, 6792, 13028, 13064, 14094, 14841, 14906, 14958, 15319, 15467,
15790, 15969, 16159, 16339, 16350, 16351, 16352, 16353, 16361, 16512,
16560, 16704, 16783, 16850, 17053, 17090, 17195, 17269, 17293, 17322,
- 17523, 17542, 17569, 17581, 17588, 17596, 17620, 17621, 17628, 17631,
- 17692, 17711, 17715, 17776, 17779, 17792, 17836, 17912, 17916, 17930,
- 17932, 17944, 17949, 17964, 17965, 17967, 17969, 17978, 17987, 17991,
- 17996, 17998, 17999, 18007, 18019, 18020, 18029, 18030, 18032, 18034,
- 18036, 18038, 18039, 18042, 18043, 18046, 18047, 18049, 18068, 18080,
- 18093, 18100, 18104, 18110, 18111, 18116, 18125, 18128, 18138, 18185,
- 18196, 18197, 18206, 18210, 18211, 18217, 18220, 18221, 18234, 18244,
- 18247, 18287, 18319, 18324, 18333, 18346, 18397, 18409, 18410, 18412,
- 18418, 18422, 18434, 18444, 18468, 18469, 18470, 18479, 18483, 18495,
- 18496, 18497, 18498, 18507, 18512, 18513, 18519, 18520, 18522, 18527,
- 18528, 18529, 18530, 18532, 18533, 18534, 18536, 18539, 18540, 18542,
- 18544, 18545, 18546, 18547, 18553, 18558, 18569.
+ 17403, 17523, 17542, 17569, 17581, 17588, 17596, 17620, 17621, 17628,
+ 17631, 17692, 17711, 17715, 17776, 17779, 17792, 17836, 17912, 17916,
+ 17930, 17932, 17944, 17949, 17964, 17965, 17967, 17969, 17978, 17987,
+ 17991, 17996, 17998, 17999, 18007, 18019, 18020, 18029, 18030, 18032,
+ 18034, 18036, 18038, 18039, 18042, 18043, 18046, 18047, 18049, 18068,
+ 18080, 18093, 18100, 18104, 18110, 18111, 18116, 18125, 18128, 18138,
+ 18185, 18196, 18197, 18206, 18210, 18211, 18217, 18220, 18221, 18234,
+ 18244, 18247, 18287, 18319, 18324, 18333, 18346, 18397, 18409, 18410,
+ 18412, 18418, 18422, 18434, 18444, 18468, 18469, 18470, 18479, 18483,
+ 18495, 18496, 18497, 18498, 18507, 18512, 18513, 18519, 18520, 18522,
+ 18527, 18528, 18529, 18530, 18532, 18533, 18534, 18536, 18539, 18540,
+ 18542, 18544, 18545, 18546, 18547, 18553, 18558, 18569.
* Cache information can be queried via sysconf() function on s390 e.g. with
_SC_LEVEL1_ICACHE_SIZE as argument.
@@ -535,3 +535,10 @@ typedef uintmax_t uatomic_max_t;
#define atomic_or(mem, mask) __arch_or_body (LOCK_PREFIX, mem, mask)
#define catomic_or(mem, mask) __arch_or_body (__arch_cprefix, mem, mask)
+
+/* We don't use mfence because it is supposedly slower due to having to
+ provide stronger guarantees (e.g., regarding self-modifying code). */
+#define atomic_full_barrier() \
+ __asm __volatile (LOCK_PREFIX "orl $0, (%%esp)" ::: "memory")
+#define atomic_read_barrier() __asm ("" ::: "memory")
+#define atomic_write_barrier() __asm ("" ::: "memory")
@@ -472,3 +472,10 @@ typedef uintmax_t uatomic_max_t;
#define atomic_or(mem, mask) __arch_or_body (LOCK_PREFIX, mem, mask)
#define catomic_or(mem, mask) __arch_or_body (__arch_cprefix, mem, mask)
+
+/* We don't use mfence because it is supposedly slower due to having to
+ provide stronger guarantees (e.g., regarding self-modifying code). */
+#define atomic_full_barrier() \
+ __asm __volatile (LOCK_PREFIX "orl $0, (%%rsp)" ::: "memory")
+#define atomic_read_barrier() __asm ("" ::: "memory")
+#define atomic_write_barrier() __asm ("" ::: "memory")